Electric stress sensing devices for crushing machines



1967 c. Y. L. LEMARDELEY ETAL 3,

ELECTRIC STRESS SENSING DEVICES FOR CRUSHING MACHINES Filed Dec. 2, 1963 United States Patent 3,300,149 ELECTRIC STRESS SENSING DEVICES FOR CRUSHING MACHINES Claude Yves Lucien Lemardeley, Paris, and Paul Marcel Emile Barret, Clichy, France, assignors to Societe Anonyme: Babbitless, Paris, France, a corporation of France Filed Dec. 2, 1963, Ser. No. 327,183 Claims priority, application France, May 17, 1963, 935,293 7 Claims. (Cl. 241-66) The present invention relates to electric devices for detecting stresses occurring in crushing machines, more particularly in gyratory crushers, due to a cramming or tamping action or to the passage across the machine of materials or bodies which resist crushing.

It is known that a crushing machine is adapted to break up the materials between cast-iron or special-steel attrition pieces. In the case of a crusher of the gyratory type, one of these pieces is located on an oscillating shaft possessed at its base with an eccentric movement, the other piece being secured on the framework of the machine.

The materials to be crushed often include bodies resisting the crushing action, for instance metal or wood fragments which, when getting in contact with the wearing pieces between which they are to be crushed, cause abnormal stresses on the various mechanical members of the machine and, especially, on the oscillatory shaft in the case of gyratory crushers.

On another hand, moist material frequently cause what may be called a cramming or tamping action, in the crushing chamber, resulting in stresses similar to those due to crush-resisting bodies, and which may lead to the breakage of the mechanical members of the crushers.

It is therefore essential to be able to detect sufficiently early such an increase of such stresses, which is substantially instantaneous in the case of the crush-resisting bodies, whilst it arises progressively in the case of cramming or tamping.

Amongst said stresses all are not always dangerous, for instance, those occurring during the passage of small-size metal pieces or fragments, or in the case of a slight cramming action in the crushing chamber; the sensing devices provided must however take account on all such stresses.

The present invention has for its object to provide an intelligently acting electrical device enabling to immediately sense the presence of foreign bodies Within the materials to be crushed, to estimate the importance thereof and detect the occurrence of any cramming or tamping action in the crushing chamber; viz. an electrical detection device of any abnormal stresses to which the crushers are being subjected.

An electric stress-sensing device for crushing machines, particularly gyratory crushers, according to the invention, comprises: a low or very low-voltage power supply connected, on one hand, to the electrically isolated shaft carrying the movable crushing members, and, on the other hand, to the framework of the crusher, whereby a servocontrol member placed in the circuit thus established is adapted to stop the crusher and/or to cause the switching in of an alarm or protection system. i

The servo-controlled member may be actuated by a contact established by the passage through the crusher of generally conductive, crush-resisting bodies. It may also be actuated through the effect of elastic deformations of a member of the crusher as said deformations are detected by an extensometric strain gauge located on the crusher in parallel across said circuit.

The gauge is preferably provided at a point where the possible deformation is at a maximum.

3,300,149 Patented Jan. 24 1967 The shaft may be isolated from the framework of the crushing machine, by establishing the suspension members thereof out of an insulating material, such as plastic and the like.

An adjustable timing mechanism may be inserted in the electric circuit in order to delay the action of said servocontrol means.

The sensing device for crushers in accordance with the present invention will now be described in more detail in the examples given hereinafter, with reference to the appended drawings, wherein:

FIGURE 1 illustrates, by way of a non limiting exapplied to a mechanically suspended gyratory crusher.

FIGURE 2 shows diagrammaticaly the device of the invention as applied to a hydraulically suspended gyratory crusher.

FIGURE 1 illustrates, by way of a non limiting example, the device as applied to a gyratory crusher wherein the oscillatory shaft 1 is isolated from the framework of the crusher by a foot-ring 2 of an insulating material, such as plastic material, for instance.

At the top, the shaft is insulated by an assembly of insulating elements including a cross-bar bearing 3 and an attrition ring 4; these elements may be also made of plastic material.

Other types of insulation may be provided in this portion of the equipment: for instance, the suspension ring 5 may itself consist of a plastic material, thus avoiding the use of an attrition ring 4 and of the cross-bar bearing 3 of insulating material.

The current is applied to the crusher, on one hand at the top of the oscillatory shaft, by means of a convenient flexible system 6, and, on the other hand, to any desired point of the framework 7.

The current may be connected to this portion of the equipment, as well as to the shaft-supporting member, i.e. to cross-bar 8, the upper framework 9, the lower frame-work 10 or to the sleeve bearing 11.

A DC. or A.C. power supply 12 feeds the circuit at a low or at a very low voltage, for safety reasons.

Inserted in the electrical circuit there is a servo-system 13 adapted to control either an alarm device, or a relay-circuit breaker 14 for the motor, or both simultaneously.

As is readily noted, when a metal piece is contained in the materials to be crushed, it will get in contact simultaneously with the crushing core member integral with the oscillatory shaft 1 and the framework and will close the circuit established as mentioned hereinabove.

The servo-control system 13, relay or the like, may break off the relay-circuit-breaker 14 of the motor and actuate a sound or luminous alarm device to signal the stopping of the machine.

Delay means controlled by an adjustable timing de-' vice may be combined with the servo-control device'13 to allow the passage of small-size metallic pieces.

The larger-sized metallic pieces, which rest a longer time in the crushing chamber, maintain the electric cir-;

cuit closed, 'thus enabling the timing device to operate and to switch in the alarm system, while switching off the relay-circuit-breaker of the driving motor of the crusher.

It is obvious that any other suitable arrangement may also be provided in this electric circuit.

To the means for sensing the presence of electrical conductive bodies are added further means adapted to control deformations produced in the mechanical members of the crusher. Such control means may consist, for instance, of an extensometric strain gauge 15 secured to shaft 1 at a suitably selected point where the deformation is maximum or on any other deformable element, such as, for instance, the arms of cross-bar 8.

The extensometric strain gauge is inserted in a circuit connected in parallel across the electric circuit already described.

The sensing device according to the invention may, of course, be applied moreover to a hydraulically suspended gyratory crusher.

FIGURE 2 illustrates the application of the device of the invention on such a crusher equipped, for instance, with a hydraulic lifting jack 16 located at the upper end of shaft 1'.

Said shaft 1' is insulated at the bottom by means of an annular member 2. and, at the top, by a cross-bar bearing 3' and a wear-ring 4'. These pieces may consist of a plastic or other insulating material.

The electrical circuit is identical to that illustrated in FIGURE 1, but the servo-control device 13' controls, in this case, the opening of a hydraulic circuit and the flow back to tank 17 of the oil feeding the jack.

As soon as the sensing is achieved, shaft 1' with its crushing core will then travel down a maximum distance, which results in giving its maximal value to the discharge opening E, at the bottom of the crushing members.

Should the material resisting to crushing be of a size smaller than said discharge opening E, it will escape and the hydraulic device, such as described in the copending application of Barret et al., Serial No. 324,544 filed November 18, 1963, will restore the shaft to its initial position.

If the metallical crush-resisting body is of too large a size for the discharge opening E, the electrical circuit will continue to remain closed and the timed delaying arrangement remains switched in, thus actuating the alarm and/ or the stopping devices of the crusher driving motor, after a predetermined interval of time.

The detection of abnormal stresses due to a cramming or tamping action and to the passage of such crushresisting bodies, as in the previous case, may also be effected by means of an extensometric strain gauge 15' secured on a suitably selected point of maximum deformation, or, again, on any other point capable of being deformed, such as, for instance, the cross-bar.

It will be apparent that, in some cases, the sensing device may carry only the electric device for detecting the presence of foreign bodies, without adjoining the extensometric strain gauge.

The examples illustrated and described hereinabove referred to the application of the sensing device to the gyratory type of crushers, but it will be readily understood that it may equally be applied to other types of crushers, for instance to roller crushers, jaw crushers, hammer crushers etc., by including only detail modifications, without departing from the spirit and scope of the invention.

What we claim is:

1. In a gyratory crusher having a framework and an oscillatory carrier shaft supported on the framework and integral with the mobile crushing core member of the machine, an electrical sensing device for detecting abnormal stresses, comprising a low-voltagev power supply, means for electrically isolating said carrier shaft from said crusher framework, an electrical circuit connecting said power supply source on one hand to said carrier shaft and on the other hand to said crusher framework, a servo-member in said electrical circuit operative upon an accidental electrical contact being established between the assembly formed by the carrier shaft and the crushing core member, on one hand, and the crusher framework, on the other, and means integral with said servo member effective to initiate stopping of the crusher.

2. In a gyratory crusher having a framework and an oscillatory carrier shaft supported on the framework and integral with the crushing core member of the machine, an electrical sensing device for detecting abnormal stresses, comprising a low-voltage power supply, a cross= bar bearing and an attrition ring, both made of insulative material and integral with the carrier shaft for electrically isolating said carrier shaft from said framework, a flexible electric circuit adapted to conduct the current from said power supply on one hand to a member integral with said carrier shaft and, on the other hand, to the frame= work, a servo-relay inserted in said electric circuit and operative upon an accidental electrical contact being established between said carrier shaft and the crushing core member on one hand, and the framework on the other, and a relay-circuit-breaker operatively controlled by said servo-relay and effective to initiate stopping of the crusher.

3. A device according to claim 1, comprising means for delaying the operation of said servo-member.

4. A gyratory crusher according to claim 1, wherein said electrical sensing device includes means for sensing the deformation of the mechanical parts of the crusher.

5. A gyratory crusher according to claim 4, wherein said means for sensing deformation comprises a second electric circuit shunted across said first electric circuit, an extensometric gauge in said second electric circuit secured to the point of maximum deformation of a member integral with the carrier shaft, and means for detecting the movements of said gauge.

6. A device according to claim 3, wherein said delaying means include an adjustable timing device.

7. In a gyratory crusher having a framework and an oscillatory shaft supported on the framework and integral with the mobile crushing core member of the machine, an electrical sensing device for detecting abnormal stresses, comprising a low voltage power supply and an extensometric stress gauge, said extensometric stress gauge being so located on said crusher as to be responsive to abnormal stress, an electrical circuit connecting said power supply and said stress gauge, a servo-member in said electrical circuit operative upon the detection of an abnormal stress by said stress gauge, and means integral with said servo-member effective to initiate stopping of the crusher.

References Cited by the Examiner UNITED STATES PATENTS 2,022,135 11/1935 Newhouse 24132 X 2,293,670 8/1942 Sickman 24133 X 2,971,704 2/1961 Joha'nsson 24l37 3,133,707 5/1964 Zimmerman 24137 \(VILLIAM W. DYER, JR., Primary Examiner. ROBERT C. RIORDON, Examiner. 

1. IN A GYRATORY CRUSHER HAVING A FRAMEWORK AND AN OSCILLATORY CARRIER SHAFT SUPPORTED ON THE FRAMEWORK AND INTEGRAL WITH THE MOBILE CRUSHING CORE MEMBER OF THE MACHINE, AN ELECTRICAL SENSING DEVICE FOR DETECTING ABNORMAL STRESSES, COMPRISING A LOW-VOLTAGE POWER SUPPLY, MEANS FOR ELECTRICALLY ISOLATING SAID CARRIER SHAFT FROM SAID CRUSHER FRAMEWORK, AN ELECTRICAL CIRCUIT CONNECTING SAID POWER SUPPLY SOURCE ON ONE HAND TO SAID CARRIER SHAFT AND ON THE OTHER HAND TO SAID CRUSHER FRAMEWORK, 